The present invention relates to a navigation system for searching for or determining the route from a starting point to a destination.
Many of the navigation systems commercially available are provided with a route searching function (see Japanese Patent Kokai Publication No. 01138409). According to this function, when a starting point and a destination are set by an input means or a current position detecting means, calculation for synthetic evaluation is made using, as parameters, the evaluation values of each road segment corresponding to the distance, the number of lanes, the road type, and the like, and the route with the best evaluation is displayed. For instance, the evaluation value for the distance is represented by Kn (Kn=10 when the distance is 10 Km), the evaluation value for the number of lanes is represented by Nn (Nn=100 for a road of a single lane, Nn=70 for a road with two lanes, Nn=50 for a road with three lanes, Nn=40 for a road-with four lanes), and the evaluation value for the type of the road is represented by Dn (Dn=2 for a highway, Dn=3 for a national road, Dn=6 for main local road, Dn=24 for other local loads). n denotes the segment number of each route. The synthetic evaluation is calculated for each of a plurality of routes from the starting point to the destination, by
.SIGMA.(Kn.multidot.Nn.multidot.Dn), PA1 a storage medium for storing segment data of the type of the road, and the distance of the road segment forming a road network, PA1 a memory means for storing evaluation values corresponding to the segment data, a route search means for searching for the route from the starting point to a destination, in accordance with a synthetic evaluation function using, as parameters, the evaluation values stored in said memory means, and PA1 further comprises
and the route having the smallest (best) synthetic evaluation is displayed being high-lighted.
However, there was a problem in that the evaluation thus determined is not necessarily optimum depending on the user, or depending on the situation. For example, some users may take the difference between a two-lane road and a three-lane road to be more significant. Also when in a hurry, the merit of the high way is increased, while when one has a plenty of time, the merit of a high way is not so high. Relying on the same evaluation under these different situations is therefore not proper.